Tertiary Carbonate Research Articles

Tectono-sedimentary evolution of the External Liguride units (Northern Apennines, Italy): insights in the pre-collisional history of a fossil ocean-continent transition zone

In the Northern Apennines, the External Liguride (EL) units are interpreted as derived from the domain that joined the Ligure–Piemontese oceanic basin to the Adriatic plate continental margin. The EL units can be divided into two different groups according to the lithostratigraphic features of the basal complexes underlying the Upper Cretaceous–Lower Tertiary carbonate flysch (e.g. Helminthoid flysch). The first group includes the western successions characterized by Santonian–Campanian sedimentary melanges where slide blocks of lherzolitic mantle, gabbros, basalts, granulites, continental granitoids are represented. The second group is represented by the eastern successions where the Cenomanian–Campanian basal complexes mainly consist of sandstones and conglomerates where the mafic and ultramafic rocks are scarce or completely lacking. Their original substrate is represented by the Middle Triassic to Lower Cretaceous, mainly platform carbonate deposits, found as slices at the base of the eastern successions. The stratigraphic features shown by the basal complexes allow the reconstruction of their source area that is assumed to be also representative for the pre-Upper Cretaceous setting. The proposed reconstruction suggests the occurrence in the EL domain of two distinct domains. The eastern domain was characterized by a thinned and faulted continental crust belonging to the Adriatic continental margin. The western domain was instead floored by subcontinental mantle associated with lower and upper continental crust, representing the ocean–continent transition. This setting is interpreted as the result of the opening of the Ligure–Piemontese oceanic basin by passive rifting, mainly developed by simple shear, asymmetric extension of the continental crust.

Palladium-catalyzed synthesis of 2,3-dihydro-2-ylidene-1,4-benzodioxins.

Palladium-catalyzed condensation of benzene-1,2-diol with various propargylic carbonates afforded regio- and stereoselectively 2,3-dihydro-2-ylidene-1,4-benzodioxins. The reaction is suggested to proceed by the formation of a (sigma-allenyl)palladium complex, followed by the intermolecular attack of the phenoxide ion on this complex to generate a new (sigma-allyl)palladium complex in equilibrium with the corresponding (eta(3)-allyl)palladium complex. Intramolecular attack of the phenoxide ion afforded the corresponding benzodioxan compound. This last attack occurs predominantly at the more electrophilic end of the (eta(3)-allyl)palladium intermediate. The Z- or E-stereochemistry of the products was established by (1)H NMR and proton NOE measurements and also by X-ray analysis on an example. The Z-stereochemistry generally observed is in agreement with the formation of this (eta(3)-allyl)palladium intermediate. However, in the case of tertiary propargylic carbonates, the E-stereochemistry generally observed could be explained by an intramolecular attack of the phenoxide ion on the intermediate (sigma-allyl)palladium complex, in slow equilibrium with the (eta(3)-allyl)palladium complex.

Tectono-sedimentary evolution of the External Liguride units (Northern Apennines, Italy): insights in the pre-collisional history of a fossil ocean-continent transition zone

In the Northern Apennines, the External Liguride (EL) units are interpreted as derived from the domain that joined the Ligure–Piemontese oceanic basin to the Adriatic plate continental margin. The EL units can be divided into two different groups according to the lithostratigraphic features of the basal complexes underlying the Upper Cretaceous–Lower Tertiary carbonate flysch (e.g. Helminthoid flysch). The first group includes the western successions characterized by Santonian–Campanian sedimentary melanges where slide blocks of lherzolitic mantle, gabbros, basalts, granulites, continental granitoids are represented. The second group is represented by the eastern successions where the Cenomanian–Campanian basal complexes mainly consist of sandstones and conglomerates where the mafic and ultramafic rocks are scarce or completely lacking. Their original substrate is represented by the Middle Triassic to Lower Cretaceous, mainly platform carbonate deposits, found as slices at the base of the eastern successions.The stratigraphic features shown by the basal complexes allow the reconstruction of their source area that is assumed to be also representative for the pre-Upper Cretaceous setting. The proposed reconstruction suggests the occurrence in the EL domain of two distinct domains. The eastern domain was characterized by a thinned and faulted continental crust belonging to the Adriatic continental margin. The western domain was instead floored by subcontinental mantle associated with lower and upper continental crust, representing the ocean–continent transition. This setting is interpreted as the result of the opening of the Ligure–Piemontese oceanic basin by passive rifting, mainly developed by simple shear, asymmetric extension of the continental crust. © 2001 Éditions scientifiques et médicales Elsevier SAS

Radarsat investigation of a circular feature in east central Jordan

A typical ring-like feature, located in east central Jordan about 150km south-east of Amman, is very obvious on Radarsat images. Four concentric circles, but only two perfect ones, were discriminated, ranging in size from about 6km to about 1km in diameter. At first glance, this feature greatly resembles an ideal impact structure. Previous geological studies, geophysical investigations and recent field observation proved the presence of a domal structure that incorporates lower Cretaceous sandstone at the core; middle of the central ring, and successively surrounded by a highly fractured and steeply dipping sequence of Cretaceous and lower Tertiary carbonates and chert. The principal faults and lineaments in the region follow N-W, N-E and E-W trends, the intersection of which is believed to have acted as a preferable place for the emplacement of an igneous body, most probably in the post-Eocene, which causes the domal uplift and the associated ring faults at Jabal Waqf as Suwwan. Interpretation of 1:60 00...

A Factor Model of the Relationship between Stream Sediment Geochemistry and Adjacent Drainage Basin Lithology, Medvednica Mt., Croatia

A mathematical model is constructed to relate the geochemical composition of recent stream material in a number of catchments on Medvednica Mt. to a broadely defined bedrock lithology which represents the parent material for the former. It is a system based factor model, which synthesizes eight lithological and 25 geochemical variables (major, minor and trace elements), reducing their relationships to six geologically meaningful factors. Five of these divulged a definite relationship between geochemistry and lithology. These are labelled as follows: factor of metamorphic rocks; factor of igneous rocks; factor of Tertiary carbonate rocks; factor of parametamorphic rocks and factor of Mesozoic carbonate rocks. Two lithologies; the Mesozoic clastic rocks and Quaternary sediments showed no clear association to any of the factors. Alternatively, one of the factors (F2) can be identified as “non-lithologic” indicating other, perhaps anthropogenic, contributions to the stream sediment geochemical composition.

Spaceborne imaging radar-C (SIR-C) observations of groundwater discharge and wetlands associated with the Chicxulub impact crater, northwestern Yucatan Peninsula, Mexico

Analyses of spaceborne imaging radar-C (SIR-C) data and field data from the northwestern Yucatan Peninsula, Mexico, demonstrate that spaceborne multifrequency polarimetric radars are excellent tools for characterizing patterns of wetland flooding. Seasonal flooding can be detected in most types of forest and marsh in the radar backscatter magnitude and phase data of both L and C band. Field observations made in the wet and dry seasons concurrent with the space missions and chemical analyses of floodwaters confirm that flooding is the product of discharge from the Yucatan aquifer, which consists of a fresh-water lens floating on seawater. This discharge controls the distribution of wetlands. Therefore, vegetation and flooding patterns, mapped with SIR-C imagery, provide valuable information on the hydrogeology of the region. Radar-image maps of wetlands and flooding indicate that there are three major zones of groundwater discharge that correlate with structures of the buried Chicxulub crater—zone 1 with the peak ring, zone 2 with the crater rim, and zone 3 with the exterior ring. Zone 1 has sulfate-poor discharge, unlike the sulfate-rich discharge in zones 2 and 3. The highest discharge is in zone 3, where the buried crater is closest to the surface. This groundwater-discharge pattern can be explained by tidal pumping of fresh water to the surface through high permeability zones developed in the Tertiary carbonates overlying crater faults and escarpments.

Quantitative determination of binary and tertiary calcium carbonate mixtures using powder X-ray diffraction.

The ability to determine the calcium carbonate polymorphic ratio of calcite, aragonite and vaterite in a mixture is important for a variety of applications, particularly the fields of biomineralisation and crystal engineering. Raman spectroscopy and powder X-ray diffraction were used to quantitatively determine the polymorphic composition of both binary and tertiary mixtures of calcium carbonate. It was found that the quantitative detection limits of powder X-ray diffraction were superior to both Raman and infrared spectroscopy.

ABSTRACT: Diagenetic processes in the impact breccia and Tertiary sedimentary carbonates of northwestern Yucatan Peninsula, Mexico

ABSTRACT: Diagenetic processes in the impact breccia and Tertiary sedimentary carbonates of northwestern Yucatan Peninsula, Mexico

Radarsat investigation of a circular feature in east central Jordan

A typical ring-like feature, located in east central Jordan about 150km south-east of Amman, is very obvious on Radarsat images. Four concentric circles, but only two perfect ones, were discriminated, ranging in size from about 6km to about 1km in diameter. At first glance, this feature greatly resembles an ideal impact structure. Previous geological studies, geophysical investigations and recent field observation proved the presence of a domal structure that incorporates lower Cretaceous sandstone at the core; middle of the central ring, and successively surrounded by a highly fractured and steeply dipping sequence of Cretaceous and lower Tertiary carbonates and chert. The principal faults and lineaments in the region follow N-W, N-E and E-W trends, the intersection of which is believed to have acted as a preferable place for the emplacement of an igneous body, most probably in the post-Eocene, which causes the domal uplift and the associated ring faults at Jabal Waqf as Suwwan. Interpretation of 1:60 000 aerial photographs and the 1:50 000 topographic maps clearly showed two concentric rings of about 6km and 1km in diameter, coinciding with the presence of steep dissected ridges of Late Cretaceous to Eocene chert and carbonates. Tectonic interpretation of gravity data showed the presence of concentric ring-like faults that greatly coincide with Radarsat imagery interpretation and field evidence. Magnetic data suggested the presence of either a dense non-magnetic igneous intrusion, a carbonate body or an anhydrite dome. Seismic data, on the other hand, confirmed the presence of a highly fractured zone about 6km wide. Merging of Radarsat with Landsat Thematic Mapper (TM) data enables discrimination of surficial deposits, chert and chalk and illustrates certain geological structures and drainage segments. Replacement of Radarsat standard (S7) images for intensity and hue in the IHS transformation and the first principal component of TM bands 7, 4 and 1 enhances lithological and main structural features.

UNAM Scientific Shallow-Drilling Program of the Chicxulub Impact Crater

A scientific drilling program is being carried out by the National Autonomous University of Mexico (UNAM) at the southern sector of the Chicxulub impact crater in the Yucatan Peninsula, Mexico. Eight boreholes, ranging in depth from 60 m to 702 m, with a total of 2.62 km of continuos core, were recovered. A high recovery rate of up to 99% (overall average recovery rate for the eight boreholes is 87%) allows us to investigate in detail the stratigraphy of the impact lithologies and the Tertiary carbonate sequence. Three of the boreholes (UNAM-5, UNAM-6, and UNAM-7, with core recovery rates from 89 to 99%) sampled impact breccias that were classified in two units—an upper breccia sequence rich in basement clasts, impact glass, and fragments of melt (suevitelike breccia) and a lower breccia sequence rich in limestone, dolomite, and evaporite clasts (bunte-like breccia). Depths of contact between the Tertiary carbonate sequence and the impact breccias are 332.0 m in UNAM-5, 222.2 m in UNAM-7, and 282.8 m in UNAM-6, giving the depth to the K/T boundary. In UNAM-7, the contact between the upper and the lower breccias is at 348.4 m, which yields a thickness of 126.2 m for the suevitelike breccia. The rest of the boreholes sampled part of the Tertiary carbonate sequence (∼200 m thick), composed mainly of limestones, dolomitized carbonates, and calcarenite, with some fossiliferous horizons.

Dolomite Formation in Caribbean Islands: Driven by Plate Tectonics?!

ABSTRACT Postdepositional dolomite occurs in the shallow subsurface of several Caribbean Islands in Tertiary and Pleistocene carbonates, e.g., on Barbados, Grand Cayman, Jamaica, and St. Croix. Recent investigations have interpreted these dolomites as relatively early-diagenetic formations from chemically modified mainly on the basis of petrography, stratigraphic association, and stable isotope values. Interpretations of the hydrologic regimes during dolomitization vary and usually include freshwater-seawater mixing, thermal or density-driven convection of seawater, or a combination thereof. This paper offers two alternative interpretations based on the relatively low Sr isotope ratios of the dolomites (0.7085 to 0.7092) and their proximity to active plate margins. Dolomitization may have been driven by plate tectonics, i.e., either by thermal convection of pore fluids at active spreading centers or by tectonic expulsion of fluids from accretionary prisms. The dolomitizing solution was seawater that was enriched in 86Sr by magmatic-hydrothermal solutions or by interaction with siliciclastics in an accretionary prism, respectively.

Carbonate Platform to Basin Transition along an Upper Cretaceous to Lower Tertiary Syrian Arc Uplift, Galala Plateaus, Eastern Desert of Egypt

ABSTRACT Biostratigraphic and facies analyses were made on Upper Campanian to Lower Eocene strata along a 58-kilometer-long dip transect across the Northern and Southern Galala plateaus, west of the Gulf of Suez. The analyses enabled us to reconstruct the evolution of a platform–slope–basin transition that is roughly parallel with the trend of the plateaus. We interpret individual sedimentary cycles as processes of a southward-prograding carbonate platform that developed along a branch of the Syrian Arc Fold Belt. The Northern Galala area was a structural high as shown by hiatuses spanning Late Cretaceous (Coniacian) to Early Paleocene times. To the south, carbonate platform progradation is evident from the Late Campanian onward. Late Cretaceous platform-derived slope deposits interfinger with basinal chalks and calcareous shales farther south. Early Tertiary carbonates were deposited in platform, slope, and basin settings. The evolution of the platform–slope–basin transition is documented by the changing large-scale depositional geometry. The evolution occurs within sedimentary sequences that are interpreted by means of a high-resolution biostratigraphic framework. The facies architecture reflects the evolution from a rimmed shelf (Late Cretaceous) to a distally steepened ramp (latest Cretaceous to Paleocene) and eventually to a homoclinal ramp (Early Eocene). The reconstruction of the imprint of fluctuating sea levels on the sedimentary record has been used to establish comparisons with age-equivalent cycles from neighboring regions.

Detection of groundwater conduits in limestones with gravity surveys: data from the area of the Chicxulub Impact crater, Yucatan Peninsula, Mexico.

Small negative gravity anomalies are found in gravity data from along the northwestern shoreline of the Yucatan Peninsula. These anomalies are shown to be due to elongate, shallow anomalous porosity zones in the Tertiary carbonates. These zones are caused primarily by groundwater solution and are presently active conduits for groundwater flow. The association of these small gravity anomalies with known topographic and structural features of the area, which partially overlies the Chicxulub Impact crater, indicates their development was influenced by structures, faults and/or fractures, within the Tertiary and pre-Tertiary carbonates.

Tertiary syntectonic carbonate platform development in Indonesia

Cenozoic tropical carbonate sedimentation was strongly influenced by local and regional tectonics in SE Asia. This paper outlines the evolution of the syntectonic Eocene to middle Miocene Tonasa Formation of South Sulawesi, evaluating controls on sedimentation, facies distribution and sequence development. Development of a facies model for this Cenozoic tropical carbonate platform provides a meaningful analogue for similar, less well‐studied SE Asian carbonates, which commonly comprise targets for hydrocarbon exploration. This study also has considerable implications for the study of syntectonic carbonates, controls on carbonate sedimentation, carbonate platform development in backarc areas and SE Asian tectonics. Detailed facies mapping, logging, petrographic and biostratigraphic analyses indicate that the Tonasa Formation was deposited initially as part of a transgressive sequence in a backarc setting. By late Eocene times, shallow‐water carbonates were being deposited over much of South Sulawesi forming a widespread (100‐km long) platform area. Shallow‐water sedimentation continued unabated in some areas of the platform until the middle Miocene. Elsewhere, active normal faulting resulted in fault‐block platforms, with local subaerial exposure of footwall blocks and the formation of basinal graben in adjacent hangingwall areas. Platform‐top facies were aggradational and dominated by larger benthic foraminifera. Low‐angle slopes, particularly hangingwall dip slopes, were characterized by the development of ramps. Faults, controlled in part by pre‐existing structures, were periodically active and formed steep escarpment margins. Variable regional subsidence strongly influenced the development of the Tonasa Carbonate Platform, whereas platform‐wide effects caused by regional eustacy have not been identified. Computer modelling of the Tonasa Platform confirms that the accommodation space and sedimentary geometries observed can be produced by block faulting and regional subsidence alone. Modelling also reveals that regional subsidence and extension, oblique to the main stretching direction, were low on the margins of the backarc basin. Shallow‐water accumulation rates for this foraminifera‐dominated tropical carbonate platform were an order of magnitude lower than those for modern warm‐water platforms dominated by corals or ooids.

ABSTRACT: Tertiary carbonate sedimentation and petroleum systems in the Papuan Fold Belt

ABSTRACT: Tertiary carbonate sedimentation and petroleum systems in the Papuan Fold Belt

Post-Miocene subtropical karst evolution, lower Suwannee River basin, Florida

Morphometric characteristics of ∼25 000 karstic depressions suggest that the last phase of the post-Miocene karstic evolution within the lower Suwannee River basin of Florida has been controlled by the lower sea-level stands of the Pleistocene and the formation of the Suwannee River. During the Pleistocene, as interglacial seas retreated, marine terraces formed by sequential sea-level lowstands and the time period of subaerial exposure diminished toward the sea. Consequently, geomorphologically younger karst landforms formed as the elevation of marine terraces decreased. The evolutionary geomorphological development of this heavily karstified region produced more frequent and/or larger and more complex depressions at higher elevations. A geographic information system analysis of morphometric and spatial distribution parameters of the karstic depressions within the lower Suwannee River basin reveals that the Florida karst is represented by broad, shallow depressions with an average density of 6.07/km 2 and an average pitting index of 14.5. Morphometric and spatial distribution parameters of karstic depressions show a great variation within the lower Suwannee River area and thus preclude a simple morphoclimatic classification of karst landforms. The Tertiary carbonate rocks of the subtropical Florida karst have relatively less joint frequency and significant primary porosity, and do not produce the extreme karst landforms observed in the massive limestones of the tropics.

Prerift and synrift sedimentation during early fault segmentation of a Tertiary carbonate platform, Indonesia

Eocene carbonate deposits of the Barru area, Sulawesi, Indonesia, provide a rare insight into sedimentation prior to and during propagation of normal faults to the surface. Three main successions; late prerift, latest prerift/earliest synrift and synrift, are characterised by distinctive facies associations and sequence development. Shallow water foraminiferal shoals and intervening lower energy depositional environments occurred during the late prerift in areas which latter formed footwall highs and hangingwall depocentres, respectively. During the latest prerift/earliest synrift, shallow water shelves deepened laterally into slope environments in developing hangingwall depocentres. In both these sequences, sections in developing hangingwall areas are thickest, deepen up-section and thin laterally towards growing footwall highs. Active faulting resulted in rapid drowning of hangingwall depocentres and massive reworking of material derived from collapse of the platform margin and adjacent shallow water/emergent footwall highs. Differential subsidence, controlling water depths and accommodation space, types of carbonate producers and active faulting were the main factors affecting depositional environments and facies distributions. Carbonate producers are extremely sensitive indicators of depositional water depth and energy, hence rapid lateral and vertical facies variations in the Barru area provide quantifiable insight into environmental changes prior to and during active faulting.

Distribution and evolution of tricyclic terpanes in lacustrine carbonates

Abundant and peculiar pairs of C20 to C25 tricyclic terpanes were discovered in the Tertiary lacustrine carbonates of the Biyang Depression. Though all organic matter contained in the entire carbonate section are of type I kerogen, the distribution of the tricyclic terpanes varies regularly with the burial depth of samples. The relative concentration of 13α(H), 14α(H) isomers in the paired tricyclic terpanes declines sharply with increasing burial depth. On the basis of this variation, new tricyclic terpane maturity parameters for immature and early mature carbonate source rocks are proposed.

Cenozoic carbonates in Borneo: case studies from northeast Kalimantan

Modern and Tertiary carbonate production is, and was, extensive and diverse in the seas surrounding Borneo, and mirrors the variety of carbonate depositional systems seen in SE Asia. The availability of favourable conditions for carbonate sedimentation around Borneo was related to a combination of factors, including tectonic setting, the formation of large basinal areas, differential subsidence providing shallow marine areas, a tropical climate and a range of local factors, such as currents or limited clastic input. A detailed sedimentological and diagenetic study was undertaken of middle Eocene to Plio–Pleistocene carbonates which developed in the north Kutai Basin and the Mangkalihat Peninsula, northeast Kalimantan. Carbonate sedimentation in this area occurred in a range of depositional environments, from mixed carbonate clastic shelves, localised and transient shoals or reefs, a variety of platform top settings to deep water redeposited carbonates. An understanding of carbonate depositional environments, spatial facies relationships, and diagenesis is essential in order to develop models for these carbonates which can be used as predictive tools in the subsurface. This study also helps to evaluate tropical carbonate development in SE Asia and the evolution of sedimentary environments in Borneo during the Cenozoic.

Recent Sedimentary Development of Tampa Bay, Florida: A Microtidal Estuary Incised into Tertiary Platform Carbonates

Tampa Bay, a large, microtidal, clastic-filled estuary incised into Tertiary carbonate strata, is the largest estuary on Florida’s west coast. A total of 250 surface sediment samples and 17 cores were collected in Tampa Bay in order to determine the patterns and controlling factors governing the recent infilling and modern sediment distribution, and to examine the results in terms of current models of estuarine sedimentation and development. Surficial sediments in Tampa Bay consist of three facies types, each occurring in a distinct zone: modern terrigenous clastic muds occurring in the upper bay and around the bay periphery; relict, reworked-fluvial, quartz-rich sands occupying the open portion of the middle bay; and modern carbonate-rich, marine-derived sands and gravels occupying the lower bay. Factors controlling sediment distribution include: sediment source and supply rate; bathymetry, which is a function of the antecedent topography; and the winnowing effect of wind-generated waves that prohibits modern accumulation in the shallow middle bay. These factors also play a major role in the recent infilling history of Tampa Bay, which has progressed in four stages during the Holocene sea-level rise. Recently developed models of estuarine sedimentation are based primarily on mesotidal to macrotidal estuaries in terrigenous clastic settings in which sedimentation patterns and infilling history are a result of the relative contribution of marine and fluvial processes. Tampa Bay differs in that it was originally incised into carbonate strata, and neither fluvial or marine processes are interpreted to be major contributors to modern sediment distribution. Tampa Bay, therefore, provides an example of an unusual estuary type, which should be considered in future modeling efforts. *** DIRECT SUPPORT *** A01BY083 00004